Despite a wide and varied body of literature, many unanswered questions remain in the field of ethanol research. Research into ethanol's effects with Drosophila melanogaster has expanded in recent years, but it still remains a young field with much to be done. The key benefit in using Drosophila as a model system for ethanol lies in the ease of genetic manipulation and the speed at which genetic modifications can be linked to behavioral phenotypes. It is a good "scouting organism" to identify candidate genes that can later be tested in more complex systems. In the first specific aim, we will conduct a large scale genetic screen to identify mutations that perturb rapid tolerance to ethanol in Drosophila. This is the first ethanol screen in Drosophila to look specifically for tolerance. Since the behavior being measured is slightly different than methods previously used, we are likely to see new results. We are using two approaches. The first is to systematically screen the entire third chromosome using large chromosomal deletions, then narrow down those results to single genes. The second approach is to screen a collection of candidate genes that have been identified by ethanol work in other model systems. Using both approaches gives us a wide net to identify genes involved in tolerance. The second specific aim is to determine the temporal gene expression patterns following ethanol exposure. mRNA will be purified from fly heads and the genes identified in aim 1 will be assayed for ethanol induced changes. For this aim, I will learn and use real-time RT-PCR. This will provide a substantial training experience that will aid in my development as a well rounded scientist. The third aim is to determine whether mutations that eliminate ethanol tolerance also influence ethanol preference behavior. The mutants identified in aim 1 will be tested, and various courses of ethanol treatment will be used to see the effects of both genotype and environment on preference to ethanol. Flies have a natural preference for ethanol, due to its presence in rotting fruit, so they are an ideal model system with which to conduct these tests. Completing these aims will not only add immediately to the ethanol research field (by identifying new genes involved in ethanol tolerance), it will add new insight into the genetics of the complex disease of alcoholism. It will expand the tools in place for the use of Drosophila as an ethanol model system. By studying how the genes of fruit flies affect their response to alcohol, we will gain an understanding of alcohol's effects that helps treatment and prevention of alcoholism in the future.